Question 1

Which of the following best describes paracrine signaling?

Accepted Answer

A cell releases signaling molecules that affect nearby cells within the same organ.

Question 2

During synaptic signaling, what is the primary molecule released by the neuron to communicate with its target cell?

Accepted Answer

Neurotransmitter

Question 3

Endocrine signaling differs from paracrine signaling in which of the following ways?

Accepted Answer

Endocrine signaling involves hormones released into the bloodstream to reach distant target cells.

Question 4

Which type of cell signaling is most likely to be involved in the rapid transmission of signals across long distances in the body?

Accepted Answer

Synaptic signaling

Question 5

Second messengers are important in cell signaling because they:

Accepted Answer

Relay signals from the extracellular environment to the cytoplasm.

Question 6

Which of the following statements about receptor proteins is correct?

Accepted Answer

Receptor proteins for polar molecules are found on the cell surface, while those for non-polar molecules are found within the cell.

Question 7

A patient is exposed to a toxin that blocks voltage-gated Na	extsuperscript{+} channels. What is the most likely effect on neuronal action potentials?

Accepted Answer

Action potentials will not be generated because depolarization cannot occur.

Question 8

Which equation best represents the Nernst equation for calculating the equilibrium potential ($$E_{ion}) of an $$ion across a membrane?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right)$$

Question 9

Which of the following best explains the 'all-or-none' law of action potentials?

Accepted Answer

Action potentials are only produced if the stimulus is strong enough to reach threshold; otherwise, none are produced.

Question 10

During the refractory period of a neuron, which of the following is true?

Accepted Answer

The neuron is incapable of responding to further stimulation for a certain period.

Question 11

Saltatory conduction in myelinated axons is characterized by:

Accepted Answer

Action potentials jumping from one node of Ranvier to the next.

Question 12

Which of the following would most likely increase the speed of action potential conduction along an axon?

Accepted Answer

Increasing the amount of myelin around the axon.

Question 13

A neuron is stimulated but the depolarization does not reach threshold. What will happen?

Accepted Answer

The depolarization will dissipate and no action potential will be generated.

Question 14

Which of the following is a correct sequence of events during an action potential?

Accepted Answer

Opening of voltage-gated Na	extsuperscript{+} channels, followed by opening of voltage-gated K	extsuperscript{+} channels.

Question 15

Which of the following best describes the role of G proteins in cell signaling?

Accepted Answer

G proteins relay signals from receptor proteins to enzymes that produce second messengers.

Question 16

If a neuron is exposed to tetrodotoxin, which blocks voltage-gated Na	extsuperscript{+} channels, what would be the expected effect on the resting membrane potential?

Accepted Answer

The resting membrane potential would remain unchanged.

Question 17

Which of the following is true regarding the frequency of action potentials in response to a stronger stimulus?

Accepted Answer

A stronger stimulus increases the frequency of action potentials.

Question 18

Which of the following best explains why myelin increases the speed of action potential conduction?

Accepted Answer

Myelin allows action potentials to jump between nodes of Ranvier, reducing the number of regions where ion movement occurs.

Question 19

Which of the following is a real-life example of endocrine signaling?

Accepted Answer

Pancreatic beta cells releasing insulin into the bloodstream to regulate blood glucose levels.

Physio: Cell Signaling, Transport, and Action Potential

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